Growth of single-crystalline β-Na0.33V2O5 nanowires on conducting substrate: A binder-free electrode for energy storage devices

We demonstrate the catalyst-free growth of single-crystalline beta-Na0.33V2O5 nanowires on a Pt-coated silicon substrate (Pt/SiO2/Si) using a chemical solution deposition method, the result of which is then used as a binder-free electrode for high-performance energy storage devices. Scanning electron micrograph indicates that nanowires with a uniform diameter of similar to 150 nm and a length greater than 5 mu m are formed. When evaluated as an electrode for supercapacitors, the crystalline beta-Na0.33V2O5 nanowires are found to have favorable characteristics, including a specific capacitance of 498 F g(-1) at a current density of 0.4 A g(-1) and a moderate rate capability with a Coulombic efficiency of 96% after 1500 cycles. In addition, the electrode shows a high energy density of 99.6 W h kg(-1) at a power density of 485 W kg(-1). Such superior capacitive performance may be attributed to the high electrical conductivity and redox pseudocapacitance, as well as intercalation pseudocapacitance, arising from the layered structure of the materials and the high crystallinity of nanowires. This outstanding electrochemical performance will make beta-Na0.33V2O5 nanowires a promising electrode material for high-performance supercapacitors. (C) 2013 Elsevier B.V. All rights reserved.